/******************************************************************************
 *
 *  Copyright (C) 2008-2012 Broadcom Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at:
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 ******************************************************************************/

/******************************************************************************
 *
 *  This file contains the implementation of the AES128 CMAC algorithm.
 *
 ******************************************************************************/

#include "bt_target.h"

#if SMP_INCLUDED == TRUE
#include <stdio.h>
#include <string.h>

#include "btm_ble_api.h"
#include "smp_int.h"
#include "hcimsgs.h"

typedef struct
{
    uint8_t               *text;
    uint16_t              len;
    uint16_t              round;
} tCMAC_CB;

tCMAC_CB    cmac_cb;

/* Rb for AES-128 as block cipher, LSB as [0] */
BT_OCTET16 const_Rb =
{
    0x87, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

void print128(BT_OCTET16 x, const uint8_t *key_name)
{
    #if SMP_DEBUG == TRUE && SMP_DEBUG_VERBOSE == TRUE
    uint8_t  *p = (uint8_t *)x;
    uint8_t  i;
    SMP_TRACE_WARNING("%s(MSB ~ LSB) = ", key_name);

    for(i = 0; i < 4; i ++)
    {
        SMP_TRACE_WARNING("%02x %02x %02x %02x",
                          p[BT_OCTET16_LEN - i * 4 - 1], p[BT_OCTET16_LEN - i * 4 - 2],
                          p[BT_OCTET16_LEN - i * 4 - 3], p[BT_OCTET16_LEN - i * 4 - 4]);
    }

    #endif
}

/*******************************************************************************
**
** Function         padding
**
** Description      utility function to padding the given text to be a 128 bits
**                  data. The parameter dest is input and output parameter, it
**                  must point to a BT_OCTET16_LEN memory space; where include
**                  length bytes valid data.
**
** Returns          void
**
*******************************************************************************/
static void padding(BT_OCTET16 dest, uint8_t length)
{
    uint8_t   i, *p = dest;

    /* original last block */
    for(i = length ; i < BT_OCTET16_LEN; i++)
    {
        p[BT_OCTET16_LEN - i - 1] = (i == length) ? 0x80 : 0;
    }
}
/*******************************************************************************
**
** Function         leftshift_onebit
**
** Description      utility function to left shift one bit for a 128 bits value.
**
** Returns          void
**
*******************************************************************************/
static void leftshift_onebit(uint8_t *input, uint8_t *output)
{
    uint8_t   i, overflow = 0, next_overflow = 0;
    SMP_TRACE_EVENT("leftshift_onebit ");

    /* input[0] is LSB */
    for(i = 0; i < BT_OCTET16_LEN ; i ++)
    {
        next_overflow = (input[i] & 0x80) ? 1 : 0;
        output[i] = (input[i] << 1) | overflow;
        overflow = next_overflow;
    }

    return;
}
/*******************************************************************************
**
** Function         cmac_aes_cleanup
**
** Description      clean up function for AES_CMAC algorithm.
**
** Returns          void
**
*******************************************************************************/
static void cmac_aes_cleanup(void)
{
    GKI_freebuf(cmac_cb.text);
    wm_memset(&cmac_cb, 0, sizeof(tCMAC_CB));
}

/*******************************************************************************
**
** Function         cmac_aes_k_calculate
**
** Description      This function is the calculation of block cipher using AES-128.
**
** Returns          void
**
*******************************************************************************/
static uint8_t cmac_aes_k_calculate(BT_OCTET16 key, uint8_t *p_signature, uint16_t tlen)
{
    tSMP_ENC output;
    uint8_t    i = 1, err = 0;
    uint8_t    x[16] = {0};
    uint8_t   *p_mac;
    SMP_TRACE_EVENT("cmac_aes_k_calculate ");

    while(i <= cmac_cb.round)
    {
        smp_xor_128(&cmac_cb.text[(cmac_cb.round - i)*BT_OCTET16_LEN], x);     /* Mi' := Mi (+) X  */

        if(!SMP_Encrypt(key, BT_OCTET16_LEN, &cmac_cb.text[(cmac_cb.round - i)*BT_OCTET16_LEN], BT_OCTET16_LEN, &output))
        {
            err = 1;
            break;
        }

        wm_memcpy(x, output.param_buf, BT_OCTET16_LEN);
        i ++;
    }

    if(!err)
    {
        p_mac = output.param_buf + (BT_OCTET16_LEN - tlen);
        wm_memcpy(p_signature, p_mac, tlen);
        SMP_TRACE_DEBUG("tlen = %d p_mac = %d", tlen, p_mac);
        SMP_TRACE_DEBUG("p_mac[0] = 0x%02x p_mac[1] = 0x%02x p_mac[2] = 0x%02x p_mac[3] = 0x%02x",
                        *p_mac, *(p_mac + 1), *(p_mac + 2), *(p_mac + 3));
        SMP_TRACE_DEBUG("p_mac[4] = 0x%02x p_mac[5] = 0x%02x p_mac[6] = 0x%02x p_mac[7] = 0x%02x",
                        *(p_mac + 4), *(p_mac + 5), *(p_mac + 6), *(p_mac + 7));
        return TRUE;
    }
    else
    {
        return FALSE;
    }
}
/*******************************************************************************
**
** Function         cmac_prepare_last_block
**
** Description      This function proceeed to prepare the last block of message
**                  Mn depending on the size of the message.
**
** Returns          void
**
*******************************************************************************/
static void cmac_prepare_last_block(BT_OCTET16 k1, BT_OCTET16 k2)
{
    //    uint8_t       x[16] = {0};
    uint8_t      flag;
    SMP_TRACE_EVENT("cmac_prepare_last_block ");
    /* last block is a complete block set flag to 1 */
    flag = ((cmac_cb.len % BT_OCTET16_LEN) == 0 && cmac_cb.len != 0)  ? TRUE : FALSE;
    SMP_TRACE_WARNING("flag = %d round = %d", flag, cmac_cb.round);

    if(flag)
    {
        /* last block is complete block */
        smp_xor_128(&cmac_cb.text[0], k1);
    }
    else /* padding then xor with k2 */
    {
        padding(&cmac_cb.text[0], (uint8_t)(cmac_cb.len % 16));
        smp_xor_128(&cmac_cb.text[0], k2);
    }
}
/*******************************************************************************
**
** Function         cmac_subkey_cont
**
** Description      This is the callback function when CIPHk(0[128]) is completed.
**
** Returns          void
**
*******************************************************************************/
static void cmac_subkey_cont(tSMP_ENC *p)
{
    uint8_t k1[BT_OCTET16_LEN], k2[BT_OCTET16_LEN];
    uint8_t *pp = p->param_buf;
    SMP_TRACE_EVENT("cmac_subkey_cont ");
    print128(pp, (const uint8_t *)"K1 before shift");

    /* If MSB(L) = 0, then K1 = L << 1 */
    if((pp[BT_OCTET16_LEN - 1] & 0x80) != 0)
    {
        /* Else K1 = ( L << 1 ) (+) Rb */
        leftshift_onebit(pp, k1);
        smp_xor_128(k1, const_Rb);
    }
    else
    {
        leftshift_onebit(pp, k1);
    }

    if((k1[BT_OCTET16_LEN - 1] & 0x80) != 0)
    {
        /* K2 =  (K1 << 1) (+) Rb */
        leftshift_onebit(k1, k2);
        smp_xor_128(k2, const_Rb);
    }
    else
    {
        /* If MSB(K1) = 0, then K2 = K1 << 1 */
        leftshift_onebit(k1, k2);
    }

    print128(k1, (const uint8_t *)"K1");
    print128(k2, (const uint8_t *)"K2");
    cmac_prepare_last_block(k1, k2);
}
/*******************************************************************************
**
** Function         cmac_generate_subkey
**
** Description      This is the function to generate the two subkeys.
**
** Parameters       key - CMAC key, expect SRK when used by SMP.
**
** Returns          void
**
*******************************************************************************/
static uint8_t cmac_generate_subkey(BT_OCTET16 key)
{
    BT_OCTET16 z = {0};
    uint8_t     ret = TRUE;
    tSMP_ENC output;
    SMP_TRACE_EVENT(" cmac_generate_subkey");

    if(SMP_Encrypt(key, BT_OCTET16_LEN, z, BT_OCTET16_LEN, &output))
    {
        cmac_subkey_cont(&output);;
    }
    else
    {
        ret = FALSE;
    }

    return ret;
}
/*******************************************************************************
**
** Function         aes_cipher_msg_auth_code
**
** Description      This is the AES-CMAC Generation Function with tlen implemented.
**
** Parameters       key - CMAC key in little endian order, expect SRK when used by SMP.
**                  input - text to be signed in little endian byte order.
**                  length - length of the input in byte.
**                  tlen - lenth of mac desired
**                  p_signature - data pointer to where signed data to be stored, tlen long.
**
** Returns          FALSE if out of resources, TRUE in other cases.
**
*******************************************************************************/
uint8_t aes_cipher_msg_auth_code(BT_OCTET16 key, uint8_t *input, uint16_t length,
                                 uint16_t tlen, uint8_t *p_signature)
{
    uint16_t  len, diff;
    uint16_t  n = (length + BT_OCTET16_LEN - 1) / BT_OCTET16_LEN;       /* n is number of rounds */
    uint8_t ret = FALSE;
    SMP_TRACE_EVENT("%s", __func__);

    if(n == 0)
    {
        n = 1;
    }

    len = n * BT_OCTET16_LEN;
    SMP_TRACE_WARNING("AES128_CMAC started, allocate buffer size = %d", len);
    /* allocate a memory space of multiple of 16 bytes to hold text  */
    cmac_cb.text = (uint8_t *)GKI_getbuf(len);
    cmac_cb.round = n;
    diff = len - length;

    if(input != NULL && length > 0)
    {
        wm_memcpy(&cmac_cb.text[diff], input, (int)length);
        cmac_cb.len = length;
    }
    else
    {
        cmac_cb.len = 0;
    }

    /* prepare calculation for subkey s and last block of data */
    if(cmac_generate_subkey(key))
    {
        /* start calculation */
        ret = cmac_aes_k_calculate(key, p_signature, tlen);
    }

    /* clean up */
    cmac_aes_cleanup();
    return ret;
}

#if 0 /* testing code, sample data from spec */
void test_cmac_cback(uint8_t *p_mac, uint16_t tlen)
{
    SMP_TRACE_EVENT("test_cmac_cback ");
    SMP_TRACE_ERROR("test_cmac_cback");
}

void test_cmac(void)
{
    SMP_TRACE_EVENT("test_cmac ");
    uint8_t M[64] =
    {
        0x6b, 0xc1, 0xbe, 0xe2, 0x2e, 0x40, 0x9f, 0x96,
        0xe9, 0x3d, 0x7e, 0x11, 0x73, 0x93, 0x17, 0x2a,
        0xae, 0x2d, 0x8a, 0x57, 0x1e, 0x03, 0xac, 0x9c,
        0x9e, 0xb7, 0x6f, 0xac, 0x45, 0xaf, 0x8e, 0x51,
        0x30, 0xc8, 0x1c, 0x46, 0xa3, 0x5c, 0xe4, 0x11,
        0xe5, 0xfb, 0xc1, 0x19, 0x1a, 0x0a, 0x52, 0xef,
        0xf6, 0x9f, 0x24, 0x45, 0xdf, 0x4f, 0x9b, 0x17,
        0xad, 0x2b, 0x41, 0x7b, 0xe6, 0x6c, 0x37, 0x10
    };
    uint8_t key[16] =
    {
        0x3c, 0x4f, 0xcf, 0x09, 0x88, 0x15, 0xf7, 0xab,
        0xa6, 0xd2, 0xae, 0x28, 0x16, 0x15, 0x7e, 0x2b
    };
    uint8_t i = 0, tmp;
    uint16_t len;
    len = 64;

    for(i = 0; i < len / 2; i ++)
    {
        tmp = M[i];
        M[i] = M[len - 1 - i];
        M[len - 1 - i] = tmp;
    }

    wm_memset(&cmac_cb, 0, sizeof(tCMAC_CB));
    SMP_TRACE_WARNING("\n Example 1: len = %d\n", len);
    aes_cipher_msg_auth_code(key, M, len, 128, test_cmac_cback, 0);
}
#endif
#endif

